Dendritic starch-based dextrin adhesives

ABSTRACT

Starch-based dextrin adhesive additives and methods of preparation are described. Adhesives containing the additive exhibit antimicrobial properties and increased water solubility. The additive contains at least one sugar unit, at least one polyphenol side chain, and at least one Frechet-type poly(aryl ether)dendron.

CROSS REFERENCE

The application claims priority to and is a divisional application ofU.S. Non-Provisional application Ser. No. 13/389,582 filed Feb. 8, 2012titled “DENDRITIC STARCH-BASED DEXTRIN ADHESIVES”, a U.S. national stagefiling under 35 U.S.C. §371 of International Application No.PCT/US2011/059942 filed Nov. 9, 2011 entitled “DENDRITIC STARCH-BASEDDEXTRIN ADHESIVES” each of which is hereby incorporated by reference inits entirety.

BACKGROUND

Modern society is extremely dependent on a steady supply of adhesives.Adhesives are used in many non-food consumer products, including books,fabricated building materials, apparel and house wares. With suchwidespread distribution and usage, the health effects of consumers'exposure to these adhesive formulations should be considered. Manycurrently available adhesive products use petroleum-based startingmaterials and require organic solvents. As these adhesives cure, theorganic solvents are released in the form of potentially harmful orirritating volatile organic compounds (VOCs). VOCs can be harmful tohuman and animal health, and are a significant cause of indoor airoutdoor water supply pollution.

Water-based (water soluble) adhesives represent an attractivealternative to petroleum-based adhesives, as water is inherentlynontoxic, non-flammable, and safe to handle. Moreover, preparation ofsuch an adhesive can be derived almost entirely from natural/renewablesources which do not produce VOCs upon curing. One such class ofwater-based adhesives are the dextrin-based adhesives. Dextrins are lowmolecular weight carbohydrates that are readily produced via hydrolysisof plant starch. This is achieved by dry roasting starch in the presenceof an acid catalyst. Corn starch is the most commonly used starch due toits abundance and low costs. Potato, tapioca and sago starches are othersubstrates that can be easily converted to dextrin. More specifically,dextrins are oligomers of D-glucose linked by either α-(1,4) orα-(1,6)glycosidic bonds. Given that these adhesives are water solublethey can therefore be distributed as water-based solutions. The majorityof starch-based adhesives are used in the paper and textile industriesas binders and sizing materials as well as glues and pastes.

Dextrins fall into three classes: white dextrins, yellow dextrins andBritish gums. These classes are differentiated by their respective dryroasting times, temperatures and amounts of catalyst used. British gumsare typically dry roasted for 10 to 24 hours at temperatures from about150° C. to about 180° C. in the presence of small amounts of acidcatalyst. British gums are the highest molecular weight dextrinfragments, and as such they typically form the strongest adhesives. Thependant hydroxyl groups form an extended network of inter- andintramolecular hydrogen bonds producing a strong adhesive force.However, the extensive hydrogen bonding network makes these longerfragments of British gum dextrins less soluble in water because thecrystalline hydrogen-bonded domains are difficult to separate anddissolve. Because of this, the utility of these starch-based dextrinadhesives is limited as the maximum solids concentration of the dextrinfragments in the water solvent carrier is only about 25% (w/v). Inaddition, these types of adhesives are susceptible to colonization by avariety of microbes including molds and fungi which can decrease theeffective lifetime of the adhesive and the product into which it isincorporated.

SUMMARY

In an embodiment, a starch-based adhesive additive includes a dendron, asugar unit bound to the dendron, and an antimicrobial agent bound to thedendron.

In another embodiment, a modified starch-based adhesive includes astarch-based adhesive and an additive, the additive including a dendron,a sugar unit bound to the dendron, and an antimicrobial agent bound tothe dendron.

In yet another embodiment, a method of synthesizing an additive includesproviding a dendron, binding a linker molecule to the dendron, binding asugar unit to the linker molecule, and binding an antimicrobial agent tothe linker molecule.

In an embodiment, a method of forming a modified a starch-based adhesiveincludes addition of an additive including a dendron, a sugar unit boundto the dendron, and antimicrobial agent bound to the dendron to astarch-based adhesive.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

DETAILED DESCRIPTION

A chemical formulation with the ability to disrupt the crystallinehydrogen bonding network so as to increase solubility of the adhesive aswell as conferring antimicrobial properties to the adhesive wouldprovide a highly desirable additive for a water-based adhesive otherwiselacking these properties. The embodiments described herein provideadhesive additives with antimicrobial properties capable of increasingadhesive solubility for multiple applications.

Various embodiments are directed to starch-based dextrin adhesiveadditives and methods of their preparation and use. Althoughstarch-based dextrin adhesives are attractive due to their low cost andadhesive strength, their widespread use is hindered by low watersolubility and a susceptibility to colonization with mold, whichshortens the lifespan of the adhesive. The additives of such embodimentsare comprised of one or more functional molecular units covalentlylinked to one another. Such additives, when added to a starch-baseddextrin adhesive in small amounts, may impart a variety of desirableproperties such as, for example, antimicrobial properties and increasedwater solubility in a single additive component. Further embodimentsinclude methods for the synthesis of an additive, as well asadditive-adhesive mixtures, methods of using the additives, and methodsof using the modified adhesives formed upon addition of the additive toan uncured starch-based adhesive.

Properties such as viscosity, solids content, stability, tack, slip,substrate penetration, drying rate, flexibility, water and microbialresistance, and cost are largely determined by the type of adhesiveused; however, certain properties can be modulated by providingadditives to adhesive compositions. For example, Borax is a commonlyused additive added to starch-based adhesives as a tackifier andviscosity stabilizer, and urea acts as a plasticizer and reduces theviscosity of an adhesive preparation.

Adhesive Additives

The additives of such embodiments include compositions that confer aproperty on an adhesive by insertion into the adhesive thereby becomingan integral part of the cured adhesive. A “functional molecular unit” ofthe additives of embodiments can include monomeric or polymeric moietiesthat confer one or more desirable properties on the adhesive whenincluded as part of the multi-functional additive. Desirable propertiesare defined as properties that impart positive effects on the adhesivesuch that the physical properties of the adhesive are enhanced or newproperties are added. For example, in some embodiments, the additive caninclude functional molecular units that act as bulking agents capable ofdisrupting the crystalline hydrogen bonding network of the adhesive, andin other embodiments, a functional molecular unit may act as anantimicrobial agent. In certain embodiments, the additive may furtherinclude at least one sugar unit that may enable integration of theadditive into the adhesive, and in other embodiments, the functionalmolecular units and/or sugar units can be covalently linked by a linkermolecule. In some embodiments, an adhesive containing one or moreadditives of the present invention make the cured adhesive more pliable,more resistant to chipping, more resistant to cracking, or moreresistant to microbial growth than a cured sample of the same adhesivein the absence of one or more additives.

In some embodiments, two or more molecular functional units can becovalently linked to one another through a molecular linker, and inother embodiments, two or more molecular functional units can be linkedto one another and a sugar unit through a molecular linker. Themolecular linker in such embodiments acts as a hub and connectingindividual molecular functional units. Thus, various molecular linkersmay include two or more reactive moieties extending from a centralmoiety. For example, in some embodiments, the linker may be1,3,5-tris(bromomethyl)benzene, which includes a central substitutedbenzene ring with bromomethyl reactive moieties at the 1, 3, and 5positions. Similar molecular linkers can include any compound having acentral aryl groups, such as, benzene, biphenyl, naphthalene,fluoranthene, phenanthrene, perylene, coronene, cycloalkyl andcycloalkenes, such as, cylcohexane, cyclopentanes cyclopentyldienes, andsubstituted aryl and cycloalkyl and cycloalkenes such as, for example,pyridines, pyrimidines, imidizoles, piperidines, morpholines,thiophenes, diazoles, pyrroles, furans, and the like. In still otherembodiments, the linker may be a linear or branched alkyl or alkene withone or more reactive groups associated with carbons along the alkyl oralkene chain. For example, in some embodiments, the molecular linker maybe a triglyceride.

Reactive moieties can be positioned at any location on the centralmoiety, and in certain embodiments, the reactive moieties may be spacedapart to allow the reactive groups of each reactive moiety toindividually react with molecular functional units. Embodiments are notlimited to any particular reactive moiety, and in some embodiments, thereactive moiety may at least include one reactive group such as, forexample, alkene, alkyne, halide, ester, epoxide, aziridine, carboxylicacid, acid chloride, carbonates, aldehydes, hydroxyl, amine, oxide,thiols, imino, imido, cyano, sulfonic acids, sulfonic esters,sulfhydryl, and the like. In some embodiments, the reactive group may bedirectly linked to the central moiety, and in other embodiments, thereactive group may be spaced from the central moiety by, for example, analkyl, alkene, or alkyne. Such spacers may include about 1 to about 10carbon atoms and may include at least one reactive group. Particularexamples, of suitable reactive groups include methylbromide,ethylbromide, acetic acid, propionic acid, propyne butyne, pentyne,methylnitrile, ethylnitrile, propionitrile, and the like.

In some embodiments, the additive may include a functional molecularunit capable of providing steric bulk covalently associated with themolecular linker. Such functional molecular units may confer increasedwater solubility of the adhesive by disruption the network of hydrogenbonds found within the adhesive molecular structure. Without wishing tobe bound by theory, disrupting the crystalline hydrogen-bonding networkof, for example, a dextrin adhesive by breaking hydrogen bonds mayincrease the solubility of the adhesive in water. Molecular functionalunits that provide steric bulk may also provide areas of amorphouspacking among tightly associated starch strands allowing for greaterdistribution of ultra-high-solid dextrin adhesives in an aqueouscarrier. Currently known suspensions of adhesives in water are limitedto less than about 25% solids due to the relatively low solubility ofunmodified dextrin-based adhesives. Adhesives including amulti-functional additive having at least one multi-functional unit thatacts a water-solubilizing plasticizer and provides steric bulk may beflexible and highly water-soluble prior to curing, and such adhesivesmay include 85% or greater solids. By adding a water-solubilizingplasticizer the additive is expected to disrupt the hydrogen bondcrystalline network resulting in increased solubility of the adhesive,and a cured adhesive that is less prone to chipping and more resistantto physical deformation.

In particular embodiments, the molecular functional unit conferringsteric bulk can be a dendritic polymer. “Dendritic polymers,” or“dendrimers,” as used herein encompass hyperbranched polymers,arboresent polymers, fractal polymers, and starburst polymers. Ingeneral, dendritic polymers have a central core, an interior structurehaving a plurality of branches extending away from the central core inevery direction, and an exterior surface with numerous end groups.Dendrimeric polymers can be constructed with tight control of size,shape topology, flexibility, and surface groups. For example, in what isknown as divergent synthesis, dendritic polymers are created by reactingan initiator core in high-yield iterative reaction sequences to buildsymmetrical branches radiating from the core with well-defined surfacegroups. In what is known as convergent synthesis, dendritic wedges areconstructed from the periphery inwards towards a focal point and thenseveral dendritic wedges are coupled at the focal points with apolyfunctional core. Dendritic syntheses can form concentric layers,known as generations, with each generation doubling the molecular massand the number of reactive groups at the branch ends so that the endgeneration dendrimer is a highly pure, uniform monodispersemacromolecule that solubilizes readily over a range of conditions. Theseproperties allow a dendron to exert significant steric bulk or sterichindrance when it is used in an additive so as to disrupt or prevent theformation of hydrogen bonds within an adhesive.

As dendrimers grow with each generation, the steric constraints fromcongestion of the branches force the polymer shape to change from astarfish-shaped molecule to a globular molecule. Dendritic growth, shapeand topology are controlled by the core, the interior branch structureand the surface groups. Dendrimers expand symmetrically in a way thatmaintains a constant terminal surface group area. In general, dendriticgrowth becomes self-limiting as steric congestion of the surfacereactive sites precludes further chemical modification.

Dendritic surfaces can have from 3 to 3072 end groups available forsurface chemistry and the number of end groups depends on the type ofdendrimer structure (which defines steric congestion) and the dendrimergeneration. Amino terminated dendrimers react with, e.g., Michaelacceptors (e.g. CH₂═CHCO₂H), α-haloesters, epoxides, aziridines,activated carboxylic acids, acid chlorides, benzyl halides, carbonates,or aldehydes. Hydroxyl terminated dendrimers react with, e.g.,halosulfonic esters, activated carboxylic acids and acid chlorides.Ester and acid terminated dendrimers react with, e.g., amines, andhalide terminated dendrimers react with, e.g., amines and alkoxide andthioalkoxide anions. Other reactive surface groups includecarboxyhalide, imino, imido, alkylamino, dialkylamino, alkylarylamino,cyano, sulfonic esters, dithiopyridyl and sulfhydryl, among others.Different surface groups may be present on different dendrons ordifferent distal groups of a dendron. The dendrimer can be solutionprocessable i.e. the surface groups are such that the dendrimer can bedissolved in a solvent. Less reactive or non-reactive end groups alsoexist. For example, ether or alkyl end groups can be used that arelargely non-reactive toward most reagents and conditions. In someembodiments, only the steric demands of the dendron are desired and endgroup functionality is avoided. In a particular embodiment, anon-reactive end group such as an alkane or ether would be desirable ifthe synthesis does not allow for a reactive end group to be present suchas when the reactive surface of the dendrimer would hinder constructionof the overall molecule.

Dendritic polymers useful in embodiments include, but are not limitedto, symmetrical and unsymmetrical branching dendrimers or dendrons,cascade molecules, arborols, and the like. In certain embodiments, thedendritic polymers can be dense star polymers. It will be appreciatedthat one or more of the dendrons attached to the core (provided that atleast one dendron is a specified conjugated dendron) can beunconjugated. Typically such dendrons include ether-type aryl dendrons,for example where benzene rings are connected via a methyleneoxy link.It will also be appreciated that when there is more than one dendron,the dendrons can be of the same or different generation (generationlevel is determined by the number of sets of branching points). It maybe advantageous for at least one dendron to be of the second, or higher,generation to provide the required solution processing properties.

In some embodiments, t-butyl and alkoxy groups have been used as surfacegroups on a dendrimer to achieve solubility in organic solvents andwater. In addition, the choice of dendron and/or surface group can allowthe formation of blends with dendrimers (organic or organometallic),polymer or molecular compounds. In some embodiments, a dendron caninclude a single chemically addressable group called the focal pointfrom which repeatedly branched low molecular weight molecules arecovalently attached to form a polymeric hyperbranched macromolecule.Dendritic molecules such as these further are characterized bystructural perfection and their ability to form spherical threedimensional structures. In particular embodiments, a dendron can be aFrechet-type dendron. Without wishing to be bound by theory, the largerthe dendron the greater the steric bulk that will be exerted on theadhesive's crystalline network and hence the greater the watersolubility increase conferred by the additive containing a particulardendron.

In certain embodiments, the dendron can be a poly(alkyl arylether)dendrimer, a generation 3 Frechet-type poly(aryl ether)dendron, ageneration 4 Frechet-type poly(aryl ether)dendron, or a generation 5Frechet-type poly(aryl ether)dendron. In other embodiments, the dendroncan be an aryl ether dendrimer, or a poly(amido amine)dendrimer, alsoknown as a PAMAM or Starburst dendrimer. In yet other embodiments, adendron will be selected that confers appropriate steric size and bulkwith only a single functional end group unblocked to enable connectionto the central core molecule.

In some embodiments, the additives can include molecular functionalunits that provide antimicrobial properties to an adhesive. In theseembodiments, the combination of the additive with an adhesive to form anadhesive, results in the adhesive becoming more resistant to growth ofat least one of mold, fungus, bacteria, and combinations thereof thanthe same adhesive in the absence of the additive. Embodiments are notlimited to a particular type of antimicrobial agent. For example, theantimicrobial agents may provide anti-bacterial, anti-viral,anti-fungal, anti-mold activities, and the like and combinationsthereof. In some embodiments, the antimicrobial agent can be a phenol orpolyphenol. Phenol or polyphenol units offer microbial resistance whenthe additive is present in the cured adhesive, which is a featurelacking in current dextrin adhesive formulations. Examples of phenol andpolyphenol units include gallic acid, modified forms of gallic acidincluding alkyl esters of gallic acid, and combinations thereof. Inother embodiments, the antimicrobial agent can be an O-alkyl quaternaryammonium salt such as, but not limited to, benzalkonium chloride,benzethonium chloride, methylbenzethonium chloride, cetalkoniumchloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofaniumchloride, tetraethylammonium bromide, didecyldimethylammonium chloride,domiphen bromide, and combinations thereof. In these embodiments, theO-alkyl quaternary ammonium salt has one ethyl group substituted for anethylene group (—CH₂CH₂—) allowing for salt to be tethered to a linkermolecule within the additive. In a particular embodiment, theantimicrobial agent comprises a quaternary ammonium salt having astructure of the formula O-alkyl-NR¹R²R³X, wherein R¹-R³ are alkylchains, and wherein X is a counterion such as a chloride ion. In stillother embodiments, the antimicrobial agent can be an organic acid. Inyet other embodiments, the antimicrobial agent can be 4-hydroxybenzoicacid, a hydroxytyrosol. In some embodiments the additive can includemore than one particular antimicrobial agent.

In some embodiments, the addition of a the additives of the presentinvention results in a modified adhesive that is more resistant togrowth of at least one of mold, fungus, bacteria, and combinationsthereof than the same adhesive in the absence of the additive.

To conform to the “click” chemistry process, the antimicrobial agentpreferably contains an O-alkyl functional group that allows fortethering to the molecular linker. In yet other embodiments theantimicrobial agent contains an ether or ester group that allowstethering to the molecular linker. In other embodiments, alcoholterminated antimicrobial agents are well suited for tethering to acentral benzene ring and can also connect to the large variety ofreactive groups that may be present around a center benzene. Theresulting complexes or linkers and antimicrobial agents are highlystable.

In further embodiments, the additive may include one or more sugar unitsthat may facilitate insertion of the additive into the adhesivemacromolecular structure. Embodiments are not limited to any particulartype of sugar because essentially any sugar molecule can facilitateinsertion into the macromolecular structure of the adhesive. Forexample, in some embodiments, the sugar unit may be a monomer oroligomer of a hexose sugar. The structure of hexose sugars closelyresemble the structure of starch-based adhesive oligomers, and thepresence of a sugar unit on the additives of such embodiments may allowthe chemical composition to become integrated into adhesive and conferthe desired properties to the adhesive. More particular examples ofhexose sugar monomers include D-glucose, D-allose, D-altrose, D-mannose,D-gulose, D-idose, D-galactose, and D-talose. These hexose sugars mayalso be in the form of oligomers either as a “pure” oligomer including asingle species of hexose sugar, or the hexose sugars may be provided asa mixture of hexose sugars including D-glucose, D-allose, D-altrose,D-mannose, D-gulose, D-idose, D-galactose, and D-talose. Where the sugarunit is an oligomer of a hexose sugar, the hexose sugars are linkedtogether by either α-(1,4) or α-(1,6)glycosidic bonds.

In an embodiment the additive is comprised of several molecularfunctional units conferring increased solubility and antimicrobialproperties to the adhesive coupled with a sugar unit. In thisembodiment, the molecular functional units and the sugar unit arecolvalently linked via a linker molecule to form the additive.

In an embodiment, the additive is a molecule that includes threefunctional units: a sugar unit, a phenol or polyphenol side chain, and aFrechet-type poly(aryl ether) dendron. The parts are covalently boundtogether, and form an additive that sterically and chemically modifiesstarch-based adhesives, such as dextrin adhesives, to prevent otherwiseuncontrolled levels of bonding between starch units of the adhesive. Inthis manner, the additive becomes an integral and interstitial unit inthe final cured adhesive. The additive imparts new or altered propertiesto the modified cured adhesive, such as reduced brittleness, increasedpliability and flexibility, antimicrobial properties, and otherdesirable properties absent in unmodified cured samples of the adhesive.The additive can be added in relatively small volume to volume amountsto starch-based dextrin adhesive stocks.

In another embodiment, the additive is a molecule that includes adendron, a sugar unit bound to the dendron, and an antimicrobial agentbound to the dendron.

Methods of Preparation

Some embodiments are directed to methods for preparing the additivesdescribed above. Such additives can be synthesized by any methodresulting in the covalent linkage of one or more molecular functionalunits and, in some cases, a sugar unit to a linker molecule such thatthe complete additive includes a single compound having covalentlylinked molecular functional groups that confer the desired properties toa starch-based adhesive. For example in some embodiments, additives suchas those described above can be synthesized by a series of successiveMitsunobu coupling reactions. In such embodiments, a linker moleculesuch as 1,3,5-tris(bromomethyl)benzene can be covalently coupled to ofeither an alcohol terminated dendron or a propargyl alcohol via aMitsunobu reaction in a first step to provide a first intermediate. In asecond step, an anti-microbial agent may then be coupled to the firstintermediate to provide anti-microbial activity to the additive. In someembodiments, a hexose sugar unit can be coupled to the linker moleculein a third step to facilitate insertion of the additive into theadhesive macromolecular structure. Of course, the order of couplingreactions can be arranged in any way. For example, an anti-microbialagent can be coupled to the linker in a first step, and a dendriticpolymer can be coupled to the linker in a second step.

In other embodiments, additives can be synthesized using “click”chemistry to connect the dendron, antimicrobial agent, and, in someembodiments, a sugar unit to a linker molecule. The process forsynthesizing an additive by this type of methodology is simple andresults in high yields. For example, a 1,3,5-tris(bromomethyl)benzenelinker 2 can be modified to replace bromines with an azide group and analkyne group at one position on the linker.

A particular example is provided below. As illustrated in the firstpanel showing a first step in a “click” chemistry method for preparing amulti-functional additive, a dendron 1 can be reacted with1,3,5-tris(bromomethyl)benzene (2) in the presence of a strong base suchas sodium hydride and to form a dendron-linker intermediate 3.

In a second step illustrated in the second panel, an antimicrobialagent, such as a derivative of pyrogallol-4-carboxylic acid salt 5 canbe coupled to the linker-dendron intermediate 3 by a two-step process.First, the linker-dendron intermediate 3 is reacted with propargylalcohol, and a base, with a tetrahydrofuran (THF) serving as a solventfor the reaction to form a second linker-dendron intermediate 4 havingan alkyne at one or more reactive groups. This second intermediate 4 isthen reacted with an antimicrobial agent 5 in the presence of an organicsolvent such as dimethylformamide (DMF) at a temperature range of 60-90°C. to create an additive 6 having an anti-microbial agent tethered to adendron through a molecular linker.

In some embodiments, a sugar group can be added to the additive 6. Asillustrated in panel 3, the additive anti-microbial and dendroncontaining additive can be combined with a hexose sugar 7 in thepresence of a catalyst such as a copper (II) catalyst and ascorbic acidand an organic solvent or water to couple the sugar to the additivefollowed by a hydrogenation reaction to form the complete additive 8.

In an embodiment, the additive of the present invention is synthesizedby a method comprising: providing a dendron, binding a linker moleculeto the dendron, binding a sugar unit to the linker molecule, and bindingan antimicrobial agent to the linker molecule. The step of binding alinker molecule to the dendron comprises reacting the dendron withsodium hydride and 1,3,5 bromomethyl benzene to form a firstintermediate followed by the step of reacting the first intermediatewith a propargyl alcohol, a base and a tetrahydrofuran to form a secondintermediate. The second intermediate is subsequently reacted with anorganic solvent and the antimicrobial agent to form a third intermediateat a temperature of about 60° C. to about 90° C. The third intermediateis in turn reacted with a sugar unit in the presence of at least onecatalyst and at least one organic solvent, followed by hydrogenation toyield the complete additive. The completed additive can then be combinedwith an adhesive, forming a modified adhesive.

Methods of Preparing Adhesives

Starch-based dextrin adhesives are a major component of the paper andpackaging industries. These adhesives are readily available,inexpensive, and easy to apply in the form of a water-based solution.They have numerous advantages over other types of adhesives includinghaving a low production cost, providing solid adhesion to poroussurfaces and oil insolubility, and being readily available, non-toxicand biodegradable. The manufacture of a generic starch adhesivetypically begins by heating the starch in water, which bursts open thestarch granules held together by internal hydrogen bonds. This forms apaste, which is used as the adhesive. Normally, above 15% starch solidscontents, this cooked paste will form an insoluble rubbery mass uponcooling; however, with the proposed additive, much higher loadingconcentrations are possible. Higher solids concentrations are desirableas currently, the usefulness of dextrin-based adhesives is limited by amaximum solids concentration of approximately 25% w/v. High solidsconcentrations are related to the strength of the adhesive. As such,dextrin based adhesives form an extended network of inter- andintramolecular hydrogen bonds that are largely responsible forconferring strength to the adhesive. It is believed that the higher thesolids concentration in the adhesive the higher the adhesive power ofthe adhesive. It is therefore desirable to achieve maximum solidsconcentrations ranging from for example 1-25% w/v, 25-50% w/v, 50-75%w/v and 75-100% w/v in a given volume of water. In some embodimentsmaximum solids concentrations will be in excess of 99% w/v, 98% w/v, 97%w/v, 96% w/v, 95% w/v, 90% w/v, 80% w/v, 70% w/v, 60% w/v, 50% w/v, 40%w/v, 30% w/v and 25% w/v. In some embodiments, the additive will conferto the adhesive in a water solvent carrier, a solids concentration ofthe modified starch-based adhesive in the water solvent carrier isgreater than 25% w/v, 30% w/v, 40% w/v, 50% w/v, 60% w/v, 70% w/v, 80%w/v, 90% w/v, 95% w/v, 96% w/v, 97% w/v, 98% w/v and 99% w/v.

Dextrin adhesives in particular are commonly prepared by heating cornstarch in the presence of acid. As mentioned above, British gums areroasted to around 170° C. for 24 hours, but suffer from low watersolubility. For British gums, the maximum usable solids content is about25%. In some embodiments, a multi-functional additive such as thosedescribed above can be added to a powdered-dextrin adhesive while thedextrin is still in the liquid (water) phase. Starch-based dextrinadhesives cure by loss of moisture. Upon evaporation of the solvent,which “cures” the adhesive, the additive can act as an internalplasticizer, held in place by its sugar unit. The dendron conferssufficient steric bulk to disrupt the insoluble crystalline network ofhydrogen bonds, and the antimicrobial agent controls the formation ofmicrobial organisms over the lifetime of the adhesive.

In an embodiment, the additives described herein allow for thepreparation of a “super-high-solid” dextrin-water adhesive, whichdecreases both shipping volume/cost as well as the required curing timesince less water is required to evaporate. The resulting adhesiveretains its strong adhesive character, is flexible, and is resistantmicrobial colonization.

In an embodiment, an additive is added to a powdered water-solubleadhesive prior to addition of water. The presence of the additive willincrease the amount of powdered adhesive that can be dissolved in aparticular amount of water and while retaining the adhesives desirableproperties and providing antimicrobial properties to the cured adhesive.

In another embodiment, an additive is added to a powdered water-solubleadhesive after the addition of water so when the adhesive is in theliquid phase but prior to curing. The presence of the additive willincrease the amount of powdered adhesive that can be dissolved in aparticular amount of water while retaining the adhesives desirableproperties and providing antimicrobial properties to the cured adhesive.

In another embodiment, an additive is added to water prior to theaddition of a powdered water-soluble adhesive. The resulting mixture ofadditive and adhesive is in the liquid phase but prior to curing. Thepresence of the additive will increase the amount of powdered adhesivethat can be dissolved in a particular amount of water while retainingthe adhesives' desirable properties and providing antimicrobialproperties to the cured adhesive.

The various preparation methods can further comprise heating the mixtureof additive, adhesive, and water. In certain embodiments, the heatingstep is applied as needed to ensure complete mixing of the additive andadhesive. The heating step can be performed at generally anytemperature. Example temperatures and ranges can include 20° C.-50° C.,50° C.-75° C. and 20° C.-75° C. In some embodiments, temperature rangeswill be lower than the boiling point of water and lower thantemperatures resulting in decomposition of organic solvents present. Theheating step can be performed for generally any length of time. Exampletimes and ranges can include 0-1 hours, 1-2 hours, 2-4 hours, 4-6 hoursand 1-6 hours. The heating step can be performed until complete mixingof the adhesive and additive is achieved. The various methods canfurther comprise cooling the mixture after the heating step. In yetother embodiments, the heating and cooling steps are accompanied byphysical mixing of the additive and adhesive mixtures. In an additionalembodiment physical mixing of the additive and adhesive mixtures isperformed in the absence of a heating or cooling step.

In yet another embodiment, the addition of an additive to an adhesivewill increase the solids content of a particular adhesive water mixtureto an amount above that which is achievable without the additive. Forexample, for British gums, the maximum usable solids content is about25% in the absence of an additive but would be increased in the presenceof an additive so that the net amount of powdered adhesive that can bedissolved in water. Specific examples of the maximum usable solidscontent are expected to be 50-75% in the presence of the additive. Insome embodiments, the desired solids content will depend of the intendeduse of the adhesive. One skilled in the art will be able to determinethe optimal solids content of an adhesive-additive mixture to meet usagerequirements. Generally, the higher the solids content, the thicker andmore viscous the adhesive-additive mixture become, and the stronger thecured adhesive will be.

In some embodiments the combination of the additive with a starch-basedadhesive to form a modified starch-based adhesive, the resultingmodified starch-based adhesive has a water solubility of about 101% toabout 200% of the same starch-based adhesive in the absence of theadditive.

Methods of Using Adhesives

A further embodiment includes using an adhesive composition comprisingthe adhesive and an additive composition to adhere a material to anothermaterial or to itself where the cured adhesive is resistant to microbialcolonization by fungi, mold, and bacteria. Examples of such materialinclude wood, paper, textile, leather, plastic, or cardboard.

The methods can comprise providing at least one material, applying theadhesive composition to the material, and adhering the material. Themethod can further comprise curing the adhesive composition. In oneembodiment, the method comprises adhering a first portion of a firstmaterial to a second portion of the same first material. In analternative embodiment, the method comprises adhering a first materialto a second material. In some embodiments, the method can compriseapplying the adhesive composition to the first portion of the firstmaterial and the second portion of the first material prior to adheringthe first portion and the second portion. In some embodiments, themethod can comprise applying the adhesive composition to both the firstmaterial and the second material prior to adhering the first material tothe second material.

The resistance to adverse factors such as microbial colonization byfungi, mold, and bacteria can be measured relative to the same curedadhesive prepared from a similar adhesive composition but lacking theadditive composition. The percent resistance can generally be anypercent resistance. Examples of percent resistance include at leastabout 10%, at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 60%, at least about 70%, at leastabout 80%, at least about 90%, at least about 95%, at least about 96%,at least about 97%, at least about 98%, at least about 99%, and rangesbetween any two of these values. In an idealized embodiment, the percentresistance is 100%, that is, the cured adhesive is completely resistantto the adverse factor.

EXAMPLES Example 1 Synthesis of a Starch-Based Dextrin Adhesive Additiveby “Click” Chemistry

A multi-functional additive can be prepared using multi-step couplingreactions. In a first step, a first, second, third, or fourth generationpolybenzylether dendron (0.48 mmol) can be dissolved in 10 mL of diethylether, followed by addition of 1,3,5-tris(bromomethyl)benzene (0.41 g,2.9 mmol). Neat Calcium hydride (19.71 mg) can be added to this mixture,and the mixture can be stirred for 24 hours at room temperature. Thesolvent can then be removed using a rotary evaporator, and the remainingcompound can be washed to remove residual 1,3,5-tris(bromomethyl)benzeneby dissolving the compound in water and washing with chloroform.

In a second coupling step, the compound produced in the first step canbe dissolved in tetrahydrofuran (THF, 10 mL), and propargyl alcohol(0.0005 mol) followed by addition of sodium hydride (10 mL 50% solutionin water). This solution can be stirred for 24 hours at roomtemperature. The resulting compound can be isolated by evaporating thesolvent in a rotary evaporator. The compound can then by dissolved indimethylformamide (DMF, 10 mL), and gallic acid sodium salt (10.0 mmol)can be added to this solution. The mixture can then be heated to 60° C.to 90° C., and stirred for 24 hours. The resulting compound shouldinclude polybenzylether dendrimers tethered to gallic acid by the1,3,5-tris(bromomethyl)benzene linker. This compound can be used as anadditive.

In a third coupling step, a sugar unit can also be added to theadditive. This can be accomplished by dissolving the additive resultingfrom the second coupling step in water and adding D-glucose (10.0 mmol),copper sulphate (CuSO₄ 0.16 mM), tertbutanol (t-BuOH, 8 mM), andascorbic acid (5.0 mM). The resulting solution can be heated to 40° C.,and stirred for 12 hours. After reacting the product can be hydrogenatedby adding Raney nickel catalyst (2-6 g, pore size 50μ and surface area90 m²/g in 50% water, nickel content 75.1%) to the reaction mixture toform the reaction slurry, heating the slurry to 45° C., and feedinghydrogen gas through the slurry at a flow rate of 1.86 liter/minuteusing a perforated glass bulb tube to keep the slurry in considerableagitation during the reaction. The resulting additive having apolybenzylether dendrimers tethered to gallic acid and D-glucose by the1,3,5 methyl benzene 1,3,5-tris(bromomethyl)benzene linker can beisolated by evaporating the solvents in a rotary evaporator, dissolvingthe compound in water, and washing with chloroform several times untilthe desired purity is reached. The solvent can be removed and theadditive can be dried and stored as a powder.

Example 2 Synthesis of a Starch-Based Dextrin Adhesive Additive by“Click” Chemistry with an Alkyne Linker

A multi-functional additive can be prepared using multi-step couplingreactions. In a first step, a first, second, third, or fourth generationpolybenzylether dendron coupled to a bromomethyl group is reacted with1,3,5-triethynyl benzene to form an alkyne-linker-dendron intermediate(1). Neat sodium hydride can be added to this mixture, and the mixturecan be stirred for 24 hours at room temperature. The solvent can then beremoved using a rotary evaporator, and the remaining compound can bewashed to remove residual 1,3,5-trimethyl benzene by dissolving thecompound in water and washing with chloroform.

In a second step, intermediate 1, an antimicrobial agent 2, prepared bytreatment of gallic acid with trimethylchlorosilane (TMSCl) and thenoxalyl chloride, can be coupled to the alkyne-linker-dendronintermediate 1 by a two-step process. First, the linker-dendronintermediate 1 is reacted with the antimicrobial agent 2, in thepresence of neat sodium hydride with a tetrahydrofuran (THF) serving asa solvent for the reaction followed by reaction with dilute hydrochloricacid to form a second linker-dendron intermediate 3 having an alkyne atone or more reactive groups and an anti-microbial agent tethered to thealkyne-linker-dendron intermediate. Intermediate 3 is reacted with asugar azide unit in the presence of copper (II), ascorbic acid,tert-butanol, water followed by a hydrogenation to yield the completedadditive 4.

Example 3 Synthesis of a Starch-Based Dextrin Adhesive Additive by“Click” Chemistry with a Halide Linker

A multi-functional additive can be prepared using multi-step couplingreactions. In a first step, 1,3,5-triodobenzene is reacted with 3equivalents of trimethylsilylacetylene, 5% palladium(II) chloridetriphenylphosphine, 5% copper (II) carboxylate, piperidines at 25° C.for 6 hours followed by reaction with potassium carbonate in methanol at25° C. for 30 minutes to form 1,3,5-triethynyl benzene.

In a second step, a first, second, third, or fourth generationpolybenzylether dendron coupled to a bromomethyl group is reacted with1,3,5-trimethyl benzene to form an alkyne-linker-dendron intermediate(2). Neat sodium hydride can be added to this mixture, and the mixturecan be stirred for 24 hours at room temperature. The solvent can then beremoved using a rotary evaporator, and the remaining compound can bewashed to remove residual 1,3,5-trimethyl benzene by dissolving thecompound in water and washing with chloroform.

In a third step, intermediate 2, and an antimicrobial agent 3, preparedby treatment of gallic acid with trimethylchlorosilane (TMSCl) and thenoxalyl chloride, can be coupled to the alkyne-linker-dendronintermediate 2 by a two-step process. First, the linker-dendronintermediate 2 is reacted with the antimicrobial agent 3, in thepresence of neat sodium hydride with a tetrahydrofuran (THF) serving asa solvent for the reaction followed by reaction with dilute hydrochloricacid to form a second linker-dendron intermediate 4 having an alkyne atone or more reactive groups and an anti-microbial agent tethered to thealkyne-linker-dendron intermediate. Intermediate 4 is reacted with asugar azide unit in the presence of copper (II), ascorbic acid,tert-butanol, and water followed by a hydrogenation to yield thecompleted additive 5.

Example 4 Synthesis of a Starch-Based Dextrin Adhesive Additive by“Click” Chemistry with an Ester Linker

A multi-functional additive can be prepared using multi-step couplingreactions. In a first step, a first, second, third, or fourth generationpolybenzylether dendron coupled to a hydroxyl group is reacted with abenzene-1,3,5-tricarboxylic acid trimethyl ester to form anester-linker-dendron intermediate (1). Neat sodium hydride can be addedto this mixture, and the mixture can be stirred for 24 hours at roomtemperature. The solvent can then be removed using a rotary evaporator,and the remaining compound can be washed to remove residualbenzene-1,3,5-tricarboxylic acid trimethyl ester by dissolving thecompound in water and washing with chloroform.

In a second step, intermediate 1 and an antimicrobial agent 2,(potassium; 3,4,5-trihydroxy-benzoate), can be coupled to theester-linker-dendron intermediate 1 by a two-step process. First, thelinker-dendron intermediate 1 is reacted with neat sodium hydride and atetrahydrofuran (THF) serving as a solvent for the reaction followed byreaction with antimicrobial agent 2 in dimethylformamide (DMF) at 100°C. and then secondly, reacted with Pent-4-yn-1-ol in the presence ofneat sodium hydride with a tetrahydrofuran (THF) serving as a solventfor the reaction to form a second linker-dendron intermediate 3 havingan at one or more reactive groups and an anti-microbial agent (2)tethered to the ester-linker-dendron intermediate. Intermediate 3 isthen reacted with a sugar azide unit in the presence of copper (II),ascorbic acid, tert-butanol, and water followed by a hydrogenation toyield the completed additive 4.

Example 5 Synthesis of a Starch-Based Dextrin Adhesive Additive by“Click” Chemistry with an Acid Chloride Linker

A multi-functional additive can be prepared using multi-step couplingreactions. In a first step, a first, second, third, or fourth generationpolybenzylether dendron coupled to a hydroxyl group is reacted at 25° C.in the presence of pyridine with a benzoyl chloride to form an acidchloride-linker-dendron intermediate. This intermediate is then reactedat 25° C. in the presence of pyridine with an antimicrobial agent (1)with the general formula HO—(CH₂)x-NR3X where R can be an alkyl group ofvariable length from 1 to 18 carbons, x can be any number from about 2to about 18 and X can be any singly charged anion such as a chloride orbromide anion, followed by a reaction with propargyl alcohol at 25° C.in the presence of pyridine to form intermediate 2. Intermediate 2 isthen reacted with a sugar azide unit in the presence of copper (II),ascorbic acid, tert-butanol, and water followed by a hydrogenation toyield the completed additive 3.

Example 6 Synthesis of a Starch-Based Dextrin Adhesive Additive by“Click” Chemistry with an Aldehyde Linker

A multi-functional additive can be prepared using multi-step couplingreactions. In a first step, a first, second, third, or fourth generationpolybenzylether dendron coupled to an ethyl-phosphonic acid diethylester group with a 3,5-Dimethyl-benzaldehyde_to form analdehyde-linker-dendron intermediate (1) by mesylation of the dendronalcohol followed by treatment with sodium iodide and triethylphosphiteat reflux.

Intermediate 1 is then reacted at 50° C. in the presence of neat sodiumhydride and a tetrahydrofuran with an quaternary amine alcoholantimicrobial agent (2) with the general formula (EtO)2(O)P—(CH2)x-NR3Xwhere R can be an alkyl group of variable length from 1 to 18 carbons, xcan be any number from about 2 to about 18 and X can be any singlycharged anion such as a chloride or bromide anion, by mesylation of thequaternary amine alcohol followed by treatment with sodium iodide andtiethylphosphite at reflux. This is followed by a reaction with ahex-5-ynyl-phosphonic acid diethyl ester (3) at 50° C. in the presenceof neat sodium hydride in a tetrahydrofuran solvent to form intermediate4 by an Arbusov rearrangement of omega-terminated bromide with triethylphosphate. Intermediate 4 is then reacted with a sugar azide unit in thepresence of copper (II), ascorbic acid, tert-butanol, and water followedby a hydrogenation to yield the completed additive 5.

Example 7 Preparation of Adhesive-Additive Mixture

The additive powder prepared as described in Examples 1-6 (0.5 mg) canbe added to dry white dextrin (100 g), and water (1 L) can be added tothis mixture to create an adhesive mixture.

The additive powder prepared as described in Examples 1-6 (500 mg) canbe added to a slurry including white dextrin (100 g) in water (1 L) tocreate an adhesive mixture.

The additive powder prepared as described in examples 1-6 (500 mg) canbe added to water (1 L) followed by addition of white dextrin (100 g) inwater (1 L) to create an adhesive mixture.

The additive powder prepared as described in Examples 1-6 (100 mg) canbe added to dry white dextrin (1000 g), and water (1 L) can be added tothis mixture to create an adhesive mixture. The additive powder preparedas described in Examples 1-6 (100 mg) can be added to a slurry includingwhite dextrin (1000 g) in water (1 L) to create an adhesive mixture.

The additive powder prepared as described in examples 1-6 (100 mg) canbe added to water (1 L) followed by addition of white dextrin (1000 g)in water (1 L) to create an adhesive mixture.

In some embodiments, the mixture of water, adhesive and additive aremixed in cold water for about 30 minutes. In yet other embodiments, themixture of water, adhesive and additive is mixed and heated to atemperature exceeding 20° C. and subsequently cooled prior to curing.

Example 8 Use of an Adhesive-Additive Mixture in the Manufacture ofCorrugated Cardboard Boxes

The adhesives prepared as described in Example 7 can be used in themanufacture of corrugated cardboard blanks for use in making cardboardboxes. Corrugated cardboard blanks are produced in a continuous two-stepoperation consisting of corrugating a strip of cardboard by means ofheated fluted rolls, applying the adhesive in Example 7 to the tips ofthe corrugations on one side, bringing a smooth cardboard liner incontact with the corrugations and forming a bond by providing pressuresufficient to hold the liner and corrugated paper in contact to form asingle faced corrugated cardboard. In a second step, the adhesive ofExample 7 is applied to the tips of the corrugated cardboard that remainexposed followed by contacting the exposed corrugated tips to a secondsmooth cardboard liner and forming an adhesive bond by providingpressure sufficient to hold the liner and corrugated paper in contact.The result of this two-step process is a stiff cardboard comprising twosmooth outer cardboard surfaces bonded to an inner core of corrugatedcardboard. The double-faced corrugated cardboard blank produced by thisprocess can be used to form boxes whereby the stiff corrugated cardboardis folded over and adhered to another portion of the same stiffcorrugated cardboard comprising a first, second, third, and fourth sidewall panel, wherein the first and third side wall panels are in opposedrelationship, and wherein the second and fourth side wall panels are inopposed relationship, the side wall panels defining an interior space ofthe box. The adhesive in Example 7 can also be utilized to adhereportions of a cardboard box to one another. In some embodiments this canbe achieved by the application of sufficient pressure so as to maintainportions of the folded cardboard blank in contact unless a bond isformed and adhesive has cured.

In some embodiments, the cardboard blank is produced as described abovewith the additional step of applying heat in conjunction with sufficientpressure to hold the liner and corrugated paper in place.

The resulting cardboard box benefits from the added features of theadhesive containing an additive. The features include greater, strengthand resistance to microbial colonization on areas where adhesive ispresent.

Example 9 Use of an Adhesive-Additive Mixture in the Manufacture ofTextile Products

The adhesives prepared as described in Example 7 can be used in themanufacture of textile products. Examples include clothing garments,household items, such as carpets and rugs, towels, curtains and sheets,furniture and automotive upholstery, and industrial belts and firehoses. Textile products can be produced by the adhesion of separatepieces of non-woven fabric or by the adhesion of a portion of a piece offabric to another portion of the same piece of fabric. Examples ofnon-woven fabrics include spunlace, spunbond, and blends of polyester,polypropylene, and/or polyethylene, as well as combinations thereof. Theadhesive described in Example 7 can be used to adhere single or separatepieces of non-woven fabrics by a process of contacting the adhesive tothe surface of fabric followed by contacting a second surface of eitherthe same piece of textile or a separate piece of textile and applyingsufficient pressure to hold the pieces of fabric in contact while theadhesive cures. The result of this process is two pieces of fabricbonded together with sufficient strength to withstand the stress of theproducts intended usage as well as resistance to colonization bymicrobial organisms at the sight of the bond.

In some embodiment, the textile product can be made as described abovewith the additional step of applying heat in conjunction with sufficientpressure to hold the pieces of textile in place.

Example 10 Comparison of Adhesive-Additive Mixture Against AdhesiveLacking Additive

The properties of a particular adhesive-additive mixture can be comparedwith those of adhesives in the absence of an additive by a number ofstandard testing methodologies including peel, tension, compression andsheer tests. These tests measure the strength of a cured adhesive andits ability to withstand a variety of stresses that can be encounteredin its use. A peel test will measure the force required to separate totwo adhered substrates, for example two pieces or fabric or two piecesof cardboard, in terms of the force, angle and time required to achieveseparation of the adhesive from the substrates. A peel test will providean indication of the level of stress required before a particularadhesive fails and separates from a substrate. Tension, compression andsheer tests allow for the characterization of adhesion provided by aparticular adhesive and the forces required to cause separation of theadhesive from a substrate or separation of two substrates adheredtogether. These tests will permit a user to evaluate the differences instrength of an adhesive with and without an additive.

In addition, tests can be performed to analyze the characteristics ofthe adhesive in the presence of an additive while the adhesive is in theliquid stage. Such tests may measure viscosity and solubility of theadhesive. The ability of an adhesive additive to increase viscosity ofan adhesive in the liquid phase can be measured by observing the rate offlow of a sample of an adhesive from one container to another positionedbelow the first container such that adhesive will flow in a constantstream under the force of gravity. The viscosity of an adhesivecontaining an additive can be compared directly to the same adhesive inthe absence of an additive while both adhesives are in the liquid phase.More sophisticated measurement devices exist to obtain a quantitativecomparison of the viscosity of an adhesive in the liquid phase. Theseinclude falling and oscillatory piston viscometers, Stabinger andStormert rotational viscometers which can be used if a particularliquid-phase adhesive is characterized a Newtonian fluid. Where theadhesive in liquid phase represents a non-Newtonian fluid theninstruments including rheometers and plastometers can be used to measureviscosity of a particular adhesive.

Increased resistance of an adhesive preparation to attack by bacteriayeast and fungi can be measured by exposing a sterile adhesive toselected microbes and monitoring the adhesives return to sterility. Inaddition, the presence of microbes on the surface or within a particularadhesive can be monitored by contacting the adhesive with a letheen agarplate and monitoring microbe growth on the agar plate. This can be doneafter specifically infecting the adhesive with a selected microbe orcontacting the adhesive with the letheen agar plate after exposure toconditions that would simulate the additives sue. These methods wouldallow for testing of adhesives with and without additives in both theliquid phase and after curing.

Additional tests can be performed to measure the performance of anadhesive containing an additive compared with the same adhesive in theabsence of an additive. Such tests might include exposure of the curedadhesive to a range of temperatures and pressures to mimic theconditions in which the adhesive would be used. Another characteristicthat can be readily measured is the performance of an adhesivecontaining an additive after varying amounts of exposure to sunlight.These conditions can be replicated under laboratory conditions byexposing the cured adhesive to varying amounts of ultraviolet light fora variety of durations and then performing the tests described above. Aswith the tests described above, the potential benefit of an additive toa particular feature of an adhesive can be quantified by comparing theadhesive in the presence of an additive to the same adhesive in theabsence of the additive.

Solubility of a water-based adhesive is an important feature that can beenhanced in the presence of an additive. To measure solubility of anadhesive powder in water, light or laser refraction can be used tomeasure the presence of particles of un-dissolved adhesive. A specifiedamount of adhesive can be added to a measured amount of water and therelative light or laser refraction can be measured as a surrogate forsolubility of the powdered adhesive. This method permits the comparisonof the solubility of a particular adhesive in the presence or absence ofan additive. An alternative method for measuring the solubility ofmeasured amounts of an adhesive with and without an additive is tomeasure adhesive sedimentation after application of a mild centrifugalforce to the adhesive-water mixture. It is expected that higher levelsof sedimentation are correlated with lower levels of solubility of theadhesive.

Furthermore, not only can the tests described above provide aquantitative measure of the benefit conferred to an adhesive by aparticular additive, these tests can also be used to determine theamounts of a particular additive that will be needed to confer orenhance the desired property in an adhesive.

In the present disclosure, reference is made to the accompanyingdrawings, which form a part hereof. In the drawings, similar symbolstypically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be used, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in theFigure, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds, compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases at least one and one or more to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or an limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrasesone or more or at least one and indefinite articles such as “a” or an(e.g., “a” and/or “an” should be interpreted to mean “at least one” or“one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 substituents refers to groups having 1, 2, or 3 substituents.Similarly, a group having 1-5 substituents refers to groups having 1, 2,3, 4, or 5 substituents, and so forth.

What is claimed:
 1. A method of synthesizing an additive, the methodcomprising: providing a dendron; binding a linker molecule to thedendron to form a first intermediate; binding a sugar unit to the linkermolecule; and binding an antimicrobial agent to the linker molecule;wherein the linker molecule is selected from, 1,3,5 bromomethyl benzene,1,3,5-triethynyl benzene, 1,3,5-triodobenzene, trimethylbenzene-1,3,5-tricarboxylate, benzene-1,3,5-tricarbonyl trichloride andcombinations thereof.
 2. The method of claim 1, wherein the dendron isselected from a generation 3 Frechet-type poly(aryl ether)dendron, ageneration 4 Frechet-type poly(aryl ether)dendron, or a generation 5Frechet-type poly(aryl ether)dendron and combinations thereof.
 3. Themethod of claim 1, wherein the sugar unit is selected from D-glucose,D-allose, D-altrose, D-mannose, D-gulose, D-idose, D-galactose, andD-talose and combinations thereof.
 4. The method of claim 1, wherein theantimicrobial agent is selected from a phenol, a polyphenol, an O-alkylquaternary ammonium salt, 4-hydroxybenzoic acid, a hydroxytyrosol andcombinations thereof.
 5. The method of claim 4, wherein the polyphenolis selected from gallic acid, a modified gallic acid an alkyl ester ofgallic acid and combinations thereof.
 6. The method of claim 4, whereinthe O-alkyl quaternary ammonium salt is selected from benzalkoniumchloride, benzethonium chloride, methylbenzethonium chloride,cetalkonium chloride, cetylpyridinium chloride, cetrimonium, cetrimide,dofanium chloride, tetraethylammonium bromide, didecyldimethylammoniumchloride, domiphen bromide, and combinations thereof.
 7. The method ofclaim 1, further comprising the step of contacting the firstintermediate with a propargyl alcohol, a base and a tetrahydrofuran toform a second intermediate.
 8. The method of claim 7, further comprisingthe step of contacting the second intermediate with an organic solventand the antimicrobial agent to form a third intermediate.
 9. The methodof claim 8, wherein the step of contacting the second intermediate withan organic solvent and the antimicrobial agent is performed at atemperature of about 60° C. to about 90° C.
 10. The method of claim 8,further comprising contacting the third intermediate with the sugar unitin the presence of at least one catalyst and at least one organicsolvent, followed by hydrogenation to yield the additive.
 11. A methodof synthesizing an additive, the method comprising: providing a dendron;binding a linker molecule to the dendron, wherein the step of binding alinker molecule to the dendron comprises reacting the dendron withsodium hydride and 1,3,5 bromomethyl benzene to form a firstintermediate; binding a sugar unit to the linker molecule; and bindingan antimicrobial agent to the linker molecule.
 12. The method of claim11, wherein the dendron is selected from a generation 3 Frechet-typepoly(aryl ether)dendron, a generation 4 Frechet-type poly(arylether)dendron, or a generation 5 Frechet-type poly(aryl ether)dendronand combinations thereof.
 13. The method of claim 11, wherein the sugarunit is selected from D-glucose, D-allose, D-altrose, D-mannose,D-gulose, D-idose, D-galactose, and D-talose and combinations thereof.14. The method of claim 11, wherein the antimicrobial agent is selectedfrom a phenol, a polyphenol, an O-alkyl quaternary ammonium salt,4-hydroxybenzoic acid, a hydroxytyrosol and combinations thereof. 15.The method of claim 14, wherein the polyphenol is selected from gallicacid, a modified gallic acid, an alkyl ester of gallic acid andcombinations thereof.
 16. The method of claim 14, wherein the O-alkylquaternary ammonium salt is selected from benzalkonium chloride,benzethonium chloride, methylbenzethonium chloride, cetalkoniumchloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofaniumchloride, tetraethylammonium bromide, didecyldimethylammonium chloride,domiphen bromide, and combinations thereof.
 17. The method of claim 11,further comprising the step of contacting the first intermediate with apropargyl alcohol, a base and a tetrahydrofuran to form a secondintermediate.
 18. The method of claim 17, further comprising the step ofcontacting the second intermediate with an organic solvent and theantimicrobial agent to form a third intermediate.
 19. The method ofclaim 18, wherein the step of contacting the second intermediate withthe organic solvent and the antimicrobial agent is performed at atemperature of about 60° C. to about 90° C.
 20. The method of claim 18,further comprising contacting the third intermediate with the sugar unitin the presence of at least one catalyst and at least one organicsolvent, followed by hydrogenation to yield the additive.